1. Field of the Invention
The present invention relates to a reinforcing device of a package for convex objects, which package is made from a folded thin sheet, the folds of which are fixed at their ends so as to impart to it resistance to vertical load.
2. Description of the Related Art
A package for convex objects, which is made from a thin, flexible sheet which, in one of its applications, makes it possible to eat a round sandwich leaving the package around the sandwich in order to collect any runs and to fold it over as the sandwich is eaten, is known from patents FR-A-2595666 and FR-A-2628719. The flexibility of the sheet makes it possible to unfold manually the folds around the convex object; indeed, during unfolding of the folds with one hand, the other hand holds the convex object by gripping it between the fingers; the more flexible the film, the less need there is to grip the convex object to hold it between the fingers; when this convex object is fragile like, for example, sandwiches of an essentially cylindrical shape generated by revolution which are produced in fast-food catering and made from brioche-type bread, there is a risk of crushing the sandwich during unfolding of the folded package; the counterpart of the flexibility of the sheet used is that the package does not protect the sandwich against crushing during transport. This shortcoming led to the idea of protecting the sandwich, when it is of cylindrical shape, with a board ring which surrounds it over its entire lateral wall, the whole then being surrounded by a thin sheet of paper. The disadvantage of such a device is that its implementation is very time-consuming and that, when it is associated with the folded package as described in the patent FR-A-352676037, it is difficult to remove the board ring without removing the folded package which, therefore, no longer performs its function of protection against runs. Within the scope of development of the folded package, attempts were made to fix the reinforcing strip directly to the thin sheet in the direction perpendicular to the folds; but the thickness of the reinforcement is limited after a short time because it soon becomes impossible to unfold the reinforcement without crushing the sandwich. To overcome this difficulty, an attempt was then made in the patent FR-A-2734791, while retaining a reinforcing strip fixed to the sheet, to leave it pre-unfolded with equal folds while the folded part of the package is folded as described previously; the problem is that, when it is associated with a flat sheet, as in the patent FR-A-2676037, which makes it possible to protect the upper and lower openings left by the edges of the folded part, it is no longer possible to stack them appropriately so as to reduce the volume they occupy during transport of the folded package.